Electric-heating system



June 7 1927.

w. E. unsow ELECTRIC HEATING SYSTEM Filed March so. 1925 2 Sheets-Sheet 1 ATTORNEY w. E. HUDSON, ELECTRIC, HEATING SY-STEM Flled March 50, 1925 June 7 1927.

INVENTOR I m .firm

ATTORNEY Patented June 7, 1927.

UNITED STATES 1,631,485 PATENT OFFICE.

WALTER E. HUDSON, OF AMAGANSETT, NEW YORK, ASSIGNOR TO HUDSON HEATING SYSTEMS, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRIC-HEATING SYSTEM.

Original application filed March 5, 1924, Serial No. 697,030. Divided and this application filed March This application is a division of my pending application Serial No. 697,030, filed March 5, 1924.

This invention relates to electrical heating apparatus for various uses but is particularly designed for heating water, either for the usual domestic purposes, or for use in a circulating system for heating the interior of a house, car or apartment or room by means of radiation from a body of such heated water or steam passing through the usual system of radiators plac d in the room or rooms which are to be kept warm.

Electricity has heretofore been used for heating rooms by exposing the conductors heated by passage of the current, directly to the atmosphere of the room, but this has been unsatisfactory because, on account of the small radiating surface of the wire maintained at a high temperature, a small amount of air brought in contact with the conductors was too highly heated, while all other parts of the room were not heated enough. Also the heated conductors so exposed to the atmosphere rapidly deteriorated and fluctuations of temperature produced were extreme, while the consumption of current was so considerable as to make the cost of operation usually prohibitive,

According to the present invention the highly heated, relatively small surface of the electrical conductor heats a somewhat larger confined body of air which circulates about the adjacent surfaces of a water container, and the Water so heated, or steam thus generated, in its turn, circulates through the usual system of radiators in the room or rooms to be heated. Consequently a large radiating surface at a moderate temperature is exposed to the atmosphere of the room, and the considerable body of heated water circulating at any given point in the system changes temperature slowly, if at all, so that practically constant room tempera ture ispreserved.

When it has been heretofore attempted to thus transfer the heat of highly resistant electric conductors to a boiler or other water heater, in the previous structures known to me, satisfactory results have not been ob tained because a part of the heat generated.

in the electric c-onductors has been lost by radiation or conduction, heat so intense as I to be destructive in its effects has been. ap plied to limited portions of the water cent Serial No. 19,203,

tainer while practically none has reached other portions, and the coils of resistance wire, when subjected to full current have been prone to expand and come in contact with the metal parts of the water container, thereby producing destructive short circuits.

My present invention overcomes these difficulties by developing an apparatus in which the heating coils of wire may be safe ly subjected to the maximum current they will stand without undergoing incipient fusion, and this without danger of short circuits, so that the maximum total heat may be produced from the most compact possible structure; the intense heat developed by the coils is evenly distributed over the largest possible area of the water container or boil er; and practically none of the heat so developed is lost by radiation or conduction.

The essential elements of the best form of apparatus at present known to me for carrying out my invention are illustrated in the accompanying two sheets of drawings in which,

Fig. 1 is a side elevation and partial sec tion of a tubular boiler with my invention applied thereto,

Fig. 2 is a cross section on line 2-2 of Fig. 1, and

Fig. 3 is an enlarged detail of the preferred form of electrical heating unit, parts being broken away and others shown in section.

Throughout the drawings like reference characters indicate like parts.

My preferred form of electrical heating unit as shown in detail in Fig. 1 is in the form of a spool and comprises a tube 2, which may be made of a refractory composition of asbestos and cementitious matter, wound with a suitable electric. conductor l of high resistance, such as nichrome wire or ribbon, and provided with enlarged ends or heads 1, 1, which are preferably made separate from the tubes so as to slip over the ends thereof. The heads 1, 1, are usually made of molded masses of carborundum. The coils of the conductor are wound on tubes 2 and are covered and kept apart by a layer ofrefractory cement 5, usually composed principally of carborundum. The ends of the coils extend outwardly through heads 1, 1, of the complete heating unit or spool as shown in Fig. 3, and are clamped p s tien y belts ea h 17 est sh wn ing the heater or boiler, from which domeoutlet pipes 10, 10, for hot water or steam extend to the usual radiators placed in the various rooms or other places to be heated, and the returning water enters the heater at the bottom from pipe 11 through short nipples 12, 12.

The enlarged ends or heads 1, 1, of the heating units or spools fit into theends of the tubes 6, and if they project therefrom, have radial openings 3, 3, connecting with the interiors of tubes 2 and thereby affording opportunity for the circulation of heated air from the interior of each unit or spool to the air space 18 formed between each tube sheet 8, and an end plate 14, of asbestos board or other refractory, non-heat-conducting material. Additional coverings 15 and 16, of less density and still greater heat insulating etliciency,are placed around the exterior of the water heater or boiler in the usual way.

Preferably the diameter of passages 33, 3, is equal to that of the bore of tube 2. The layers 15, 15 of non-heat-conducting covering are preferably made of air cell material as indicated in the drawings. The outer covering 16 is applied in plastic condition as a mortar to completely seal the boiler from the atmosphere, and usually is an asbestos composition. The return water pipe 11 is also usually protected by similar nonheat-conducting covering 21. 4

In operation the coils 4: are intensely heated by the electric current and transfer this heat at a lesser temperature to the tubes2 on which they are wound and to the cement envelopes 5, and heads 1, 1. The air confined in the annular spaces 19, between the envelopes 5 and the boiler tubes 6, rises, when thus heated by envelopes 5, comes in contact with the upper portion of each tube 6, ives up a portion of its heat to the water above the tube, then passes down along the walls of tubes 6 to the lowest point therein and rises again around the heating unit to take up more heat therefrom. This confined bodyof air thus acts as a transfer agentmoving ina closed path to carry heat. from ,the envelope 5 to the water surrounding tube 6. In much the same way the heated air in tubes 2 of each'heat-ing unit or spoolpasses out through the upper ventilatingv opening 8 (these openin s- 3 in spool heads I, being arranged vertically, as shown in section and indotted lines in Figs. 1 and 2) into air spaces 13, 13, and along the tube sheets 8,

transferring heat to these tube sheets and to the water on the inner sides thereof. The air so cooled by contact with the tube sheets then drops down to the bottom of air spaces 13, to be forced up and into the interiors of tubes 2 again for reheating, thus acting as a transfer agent to carry heat from the interiors of the heating units or spools to the tube sheets, or boiler heads. These currents of air are indicated by the arrows in Fig. 2. The projecting spool heads 1, also transmit heat from the tubes 2 and envelopes 5 to the air circulating in spaces 13, 13, and the entire spool structure is thus kept at a more moderate ten'iperature and they are thus less likely to disintegrate from over heating.

The advantages of my invention comprise the long life of the electrical heating unit or spools including the coils of wire which are embedded therein and so protected from oxidation and possible short circuiting, thestep down transformation of the intense heat of the coils through refractory envelopes, and air envelopes to the tubes and tube sheets of the boiler, the even distribution of heat from the exteriors of the spools to the interiors of the boiler tubes and from the interiors of the spools and from the spool heads to the boiler tube sheets, and the complete scaling in of all this heat by the surrounding airtight, non-heat-conducting covering so that practically none of it can be lost, but all must be absorded by the water passing through the boiler. The form of electrical heating units here shown can also be readily removed from the boiler tubes for replacement or repair after loosening nuts 18 and disconnecting the circuit wires 20.

Obviously other materials might be sub stituted for some of those mentioned above and the forms, proportions and arrangen'ient of parts varied within limits without departing from the underlying principles of my invention or entirely sacrificing the beneficial results above described.

Having described my invention, I claim:

1. The combination, with a tubular boiler, of a plurality of electric'heating elements adapted to be inserted. in the tubes of such boiler, veach of said heating. elements being composed of a spool having heads adapted to fit closely into a boiler tube, an intermediate portion of less diameter on which a coil of resistance wire is wound, and an electrically insulating coatin mass of refractory material in which said coil is embedded, the exterior diameter of said spool coatin being less than the diameter of the spoo heads. whereby. closed annular spaces are found between said spool and its containing tube in which spaces the air heated by contact with the spool'may circulate.

' 2. The combination, with atuhular boiler, of a plurality of hollow spools of refractory material inserted in the tubes thereof, said spools having heads adapted to fit closely into the ends of said tubes and intermediate portions of nearly as large diameter, where by closed annular air spaces of very small radial dimensions are formed in said tubes, coils of resistance wire wound on said spools and means for supplying electric current to said coils, together with a non-heat-conductin; covering for said boiler, the portions of which covering opposite the boiler tube sheets are spaced away therefrom to form air spaces into which the spool ends open.

3. A. combination such as set forth in claim 2 in which portions of said spool heads project into said last mentioned air spaces.

4. A combination such as set forth in claim 2 in which portions of said spool heads project into said last mentioned air spaces and open into the same through vertically arranged perforations connected to the spool interiors.

5. The combination, with a tubular boiler, of a plurality of hollow spools of refractory material inserted in the tubes thereof, said spools having heads adapted to fit closely into the ends of said tubes, whereby closed annular air spaces are formed in said tubes, coils of resistance w re Wound on sa1d spools and means for supplying electric current to said coils, together with a non-heat-conducting covering for said boiler, the portions of which covering opposite the boiler tube sheets are spaced away therefrom to form air spaces into which the spool ends open, said non-heat-conducting covering comprising solid plates of fireproof material placed opposite said tube sheets, layers of air cell covering surrounding said plates and the cylindrical shell of the boiler, and a plastic coating outside said air cell layers forming an airtight enclosure for the entire structure.

(3. The combination, with a tubular boiler, of a series of spools of refractory material set in the tubes of said boiler, the heads of said spools fitting closely in the ends of said tubes and having perforations lengthwise thereof, coils of wire wound on said spools with their terminals extending out into said perforations, bolts of conducting material passing through said perforations, in contact with said wires, and electrical connections to the outer ends of said bolts.

7. A combination such as set forth in claim 6 in which the means for producing said electrical connections comprise nuts screwed on the projecting bolt ends and also acting to hold said bolts in position.

WALTER E. HUDSON. 

